Sewing machine

ABSTRACT

A mechanism in a sewing machine for producing a stretch stitch sewing pattern of alternating forward and reverse feed strokes including cam means operating in timed relationship to the main shaft and manually controlled linkage for selectively transmitting cam movement to a feed control slide. Various elements of the mechanism are arranged to move in planes parallel to the plane of movement of the feed control slide to provide mechanical simplicity and reliability and avoid adjustment sensitivity and operating noise. Preferably, the control slide is spring biased to a forward feed position and moved to a reverse feed position by the linkage so that the mechanism may be engaged or disengaged at any point in a machine cycle whether or not the machine is operating.

United States Patent Seiriki Mar. 12, 1974 SEWING MACHHNE Primary ExaminerWerner H. Schroeder [75] Inventor: Matsuzo Seiriki, Shijonawate, Japan Attorney Agent or FIrm'TMCNCnny Famngton Pearne & Gordon [73] Assignee: White Sewing Machine Company, Cleveland, Ohio [22] Filed: Aug. 16, 1972 [57] ABSTRACT [2]] App! No: 281,176 A mechanism in a sewing machine for producing a stretch stitch sewing pattern of alternatmg forward and reverse feed strokes including cam means operat- U-S. Cl. in timed relationship to the main haft and manu- [5 l 1 Int. controlled linkage for electively transmitting cam Field of Search 1 12/153 1 158 A, 158 B, movement to a feed control slide. Various elements of 1 12/2031 21 213, 215 the mechanism are arranged to move in planes parallel to the plane of movement of the feed control slide to [56] References Cited provide mechanical simplicity and reliability and avoid UNITED STATES PATENTS adjustment sensitivity and operating noise. Preferably, 2,982,241 5/1961 Fujita 112/210 the control Slide is Spring biased to a forward feed P 3,060,875 10/1962 11ml 1. 112 210 x i ion and moved to a reverse feed position by the 3,088,427 5/1963 Brusaglioni l l2/2l0 linkage so that the mechanism may be engaged or dis- 3,467,()4() 9/1969 Hacklander ll2/2l0 engaged at any point in a machine cycle whether or not the machine is operating.

13 ClaimsQS Drawing Figures PATENIEDIAR 1 2 m 3.796.1 72

sum 2 OF 2 1 SEWING MACHINE BACKGROUND OF THE INVENTION The invention relates to improvements in sewing machines and, in particular, pertains to a manually controlled mechanism for producing a stitch pattern characterized by high lengthwise elasticity.

DESCRIPTION OF THE PRIOR ART Conventional domestic sewing machines produce a lock stitch scam in which separate needle and bobbin threads are interlocked at each needle penetration along the seam. As in the usual case where the stitch pattern is a simple succession of advance feed strokes, the lengthwise elasticity of the seam produced by the threads is limited to that of the threads themselves. While not a significant problem when sewing closely woven fabrics, use of a simple lock stitch scam in a relatively stretchable fabric, such as a knit material, may cause serious problems. The sewing threads may limit the natural stretch ofthe fabric and result in unsightly puckering of the fabric when areas adjacent the seam are stretched. Moreover, the threads are more susceptible to breakage when tension is applied along the seam since the load is concentrated on the threads rather than distributed in the fabric.

One recognized approach to providing stretch at a seam is to alternate forward and reverse feed strokes. By using more forward motion than rearward motion in the stitches a net forward feed results. The overlapping stitch portions at each reverse stitch form loops which constrict to donate thread to fabric stretching areas intermediate the reverse stitches when subjected to lengthwise tension.

The prior art includes various mechanisms to generate alternate forward and reverse stitches. Generally these devices have been incorporated on the more sophisticated machines and have not been widely used primarily because of their relatively high cost. On the other hand, various arrangements have been suggested for use in standard or moderately complex machines. In this category, the known arrangements have not been completely satisfactory. Certain devices have required the use of compound linkages and drive members each operating in a plurality of planes. Such devices are usually expensive to manufacture and assemble, are difficult to accurately adjust, and unless accurately made produce excessive operating noise. Certain of these devices require that the machine be turned off before manual engagement and disengagement of the mechanism and may be knocked out of adjustment or permanently damaged if an operator inadvertently attempts to shift the mechanism while the machine is runnmg.

SUMMARY OF THE INVENTION The invention provides a simplified mechanism for use in a conventional sewing machine for producing a stretch stitch pattern. The output motion of the mechanism oscillates a feed regulator slide of conventional design on successive feed strokes so that the feed stroke alternates in direction on successive strokes. Various elements of the mechanism are arranged for movement in planes parallel to the feed slide plane to achieve kinematic efficiency. Ideally, the mechanism comprises a series of pivotal links selectively actuated by cam means including a constantly rotating cam.

Since motion is limited to parallel planes complex mechanical linkages are avoided. As a result, the mechanism is relatively inexpensive to manufacture and assemble. The absence of lost motion and excessive clearance between connected members permits the mechanism to operate without objectionable noise and without wear producing impact loads. Further, cam means and a cam follower of the mechanism are arranged to be engaged while the machine is running at any point in a stitch cycle. The mechanism therefore cannot be damaged by inadvertence of the operator during engagement or disengagement when the machine is running.

In the preferred arrangement, a set of spur gears driven from the main shaft of the machine provide a synchronous speed reduction for driving the rotating cam preferably at half speed to pivot the feed slide on every other stitch cycle. The spur gears, cam means,

cam follower and other associated elements rotate or pivot in parallel planes.

The feed control slide is conveniently biased to a forward feed position by a spring. In operation, the mechanism pivots the slide to a reverse feed position against the spring force on alternate feed strokes. A manually operable selector lever is effective to engage and disengage the mechanism. The selector lever adjusts the relative position of the cam means and follower such that the follower generates movement of the feed control slide only when the selector is in an operative position There are no interfitting elements such as pins or slots to be aligned for engagement or disengagement of the mechanism and, consequently, there is no unique angular position of the cam at which the manualselector must be engaged or disengaged. Accordingly, the selector lever may be shifted without damage to the mechanism at any point in a stitch cycle whether or not the machine is running.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a stitch control apparatus embodying the principles of the invention showing'the relationship of the apparatus with various conventional parts of a sewing machine.

FIG. 2 is an elevational view of the apparatus illustrated in a nonoperative position.

FIG. 3 is a perspective view of a manually operable selector lever of the apparatus shown in a nonoperative position corresponding to FIG 2.

FIG. 4 is an elevational view of the apparatus similar to FIG. 2 but illustrating the apparatus in an engaged or operational position.

FIG. 5 is a view similar to FIG. 4 again showing the apparatus in an operational position but illustrating a rotating cam in a position opposite that illustrated in FIGS. 2 and 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, there is illustrated a stitch control mechanism 10 in a sewing machine, the latter having fragments 12 of its frame indicated at relevant areas in FIG. 1. A main shaft 14 of the sewing machine normally extends longitudinally from a standard through a bracket arm (both not shown) of the machine. In a conventional manner, the main shaft 14 is driven by a motor and in turn drives the various elements of the machine including the needle and hook.

Among the elements driven by the main shaft 14 is a conventional connecting rod 16 journaled on an cecentric or crank portion 17 of the main shaft. The con necting rod 16 extends downwardly from the main shaft 14 in the standard to the lower or bed portion (not shown) of the machine where it imparts oscillating motion to the hook and raises and lowers the feed dog (also not shown) of the machine. Adjacent the crank portion 17 on the main shaft 14 is a constant breadth cam 18. Engaging the cam 18 across its width is a forked or bifurcated pitman 19. In a known manner, the pitman 19 is vertically supported and pivotal on a slide block 22 slidably mounted in a groove 25 ofa feed control slide 23 of generally conventional design.

The control slide 23 is pivotally mounted on the frame 12 by a cantilevered pin 24. The inclination of the feed control or regulator slide 23 determines the direction and amplitude of the feed stroke of the feed dogs. A tension spring 26 is hooked on a pin 27 projecting from the control slide 23. A lower end (not shown) of the spring 26 is anchored to the frame so that the spring biases the control slide 23 in a clockwise direction as viewed in FIG. 1. Clockwise movement of the control slide 23 is limited by an adjustable bracket 29 pivotal on the cantilevered pin 24 separately from the control slide 23. Clockwise rotation of the bracket 29 is limited by an upstanding projection 31 fixed to a feed control rod 32. The control rod 32, in a known manner, extends from a button on the face of the machine. The button may be manually engaged to move the control rod 32 rightwardly as viewed in FIG. 1 to reverse the direction of sewing by causing the control slide 23 to rotate in a counterclockwise direction and assume a different inclination from that shown in FIG. 1. The control rod projection 31 operates on the bracket 29 through a pin 33 fixed on the bracket. A screw 34 threaded into the bracket 29 and abutting the control slide 23 provides adjustment between the control slide and control rod 32. A spring rod 35 maintains contact between the adjusting screw 34 and control slide 23.

Positively driven by the main shaft 14 is a set of spur gears 41 and 42. The smaller gear 41 is fixed on the main shaft 14 directly while the larger gear 42 is rotatably mounted on a bracket plate 43. As illustrated in FIGS. 2, 4 and 5, the bracket plate 43 includes an upstanding leg 44 having aipair of mounting holes 45 through which screws may be positioned to fix the bracket 43 to the frame of the sewing machine. The mounting holes 45 are elongated to provide adjustment of the center to center distance of the gears 41 and 42. The larger gear 42 is rotatably mounted on the bracket plate 43 with a shoulder screw 47 and a nut 48. The larger gear 42 has a pitch diameter exactly equal to twice the pitch diameter of the smaller gear 41. Inte- I grally formed with the larger gear is a triangular cam 51.

A cam follower link 54' is biased against the cam 51 by a tension spring 55 hooked at one end 56 to the link and at a lower end 57 to a bracket 58 fixed to the frame of the machine. The cam follower link 54, as shown, may be formed of sheet metal with a triangular shape bent over along an edge to form a cam following lip 59. At one of its corners, the triangular cam follower link 54 is pivotally mounted by a screw 61 threaded into a crank arm 62. The crank arm 62 is fixed on a pivot shaft 64 by a lock screw 65. The pivot shaft 64 is pivotally mounted in a hole (not shown) in the bracket 43 and is retained against end movement relative to the bracket by a set collar 67. At an end 69 opposite the bracket 43, the pivot rod 64 is pivotally supported in a bore 70 in an adjacent area of the frame 12. Fixed to this end 69 of the rod 64 is a control slide actuating lever 72. At an outer end of the lever 72 is an offset pin 73 adapted to engage the underside of the control slide 23.

On an end of the follower link 54 opposite the pivoted end there is provided a fixed cam follower pin 76. The follower pin 76 is adapted to engage a camming surface 77 formed by one leg 78 of a selector lever 79. The selector lever 79 is pivotally mounted on a shoulder screw 80 fixed into a lower end of the bracket plate 43. Extending generally at right angles to the leg 78 is a second lever leg 81. The latter leg 81 projects forwardly beyond a plate 82 on the front face of the sewing machine. A spherical knob 84 is conveniently attached to the outward end of the lever 79 to provide a finger grip for manual operation. The plate 82 is formed with a first or lower notch 86 and an upper or second notch 87.

Preferably, the lever 79 is arranged so that it will tend to remain in the plane of the notches 86 and 87 but is mounted with enough resilience to permit it to be manually deflected out of the plane to the right as viewed in FIG. 3 to enable it to be released from either of the notches 86 or 87 and moved to the other. It will be understood that either of the notches 86 and 87 will lock the lever 79 in a corresponding position. As explained below, the position of the lever 79 illustrated in FIGS. 2 and 3 renders the mechanism 10 inoperative, while the position illustrated in FIGS. 4 and 5 renders the mechanism operative.

In operation, the mechanism 10 is effective to reverse the direction of sewing before each feed stroke. This direction reversal on each successive stroke follows from the 2:1 ratio of the gears 41 and 42. The cam 51 develops its maximum radial displacement at every other revolution of the main shaft 14 and its minimum radial displacement at intervening revolutions of the main shaft. As detailed below, the cam 51 through various levers ultimately causes automatic feed reversal by oscillation of the control slide 23.

In a conventional manner, the direction of feed of the feed dogs is determined by the direction of generally vertical movement imparted to the pitman 19 by the feed slide 23. The pitman cam 18 causes the upper end of the pitman 19 to move laterally or horizontally. Horizontal movement of the upper end of the pitman 19 causes the slide block 22 to move along the slide groove 25 in the control slide 23. Depending on the inclination of the control slide 23 the pitman may move up or down with the slide block 22. For example, linkage (not shown) to the feed dog from a lower end of the pitman 19 may be arranged to feed forwardly when the pitman moves upwardly and feed rearwardly when the pitman moves downwardly.

The mechanism 10 is effective to automatically oscillate the control slide 23 when the pivot rod 64 is oscillated between the proper limits. Referring specifically to FIG. 2, with the manual lever 79 in the inoperative position, the cam follower lever 54 is vertically oscillated or reciprocated by the cam 51. This oscillation of the follower lever 54 is ineffective to pivot the pivot shaft 64 because the pivot lever 54 can simply rotate about the screw 61 to accommodate changes in position of the cam 51. With the selector lever 79 in the position illustrated in FIGS. 2 and 3, the sewing machine will operate in aconventional manner sewing only forward stitches.

With reference to FIGS. 4 and 5, when the selector lever 79 is in the upper or operative position of the notch 87, the cam 51 in cooperation with the cam surface 77 is effective to cause oscillation of the pivot shaft 64 and control slide 23. The relative position of the elements of FIG. 5 is the same position illustrated in FIG. 1. In this position the offset pin 73 on the pivot rod lever 72 has just begun to contact the underside of the control slide 23.

Rotation of the cam 51 from the position illustrated in FIG. 5 to the position illustrated in FIG. 4 causes the follower lever 54 to swing upwardly. During this vertical swinging the follower pin 76, and therefore the cam follower link 54, is caused to move leftwardly. This leftward movement of the follower link 54 causes a corresponding displacement of the crank arm 62 and rotation of-the pivot rod 64. Rotation of the pivot rod 64 causes the offset pin 73 to move the control slide counterclockwise from the position illustrated in FIG. 1. Additional rotation of the cam 51 allows the follower link 54 to return from the positionillustrated in FIG. 4 to that of FIG. 5 and the control slide 23 back to the position illustrated in FIG. 1.

The mechanism is arranged such that the reverse stroke is less in amplitude than the forward stroke so that a net forward feed results. It has been found that a practical ratio of forward feed to rearward feed amplitude is 2:1 although this ratio may be adjusted to suit particular conditions. The resulting stitch pattern as indicated above is characterized by a high degree of lengthwise elasticity and is therefore particularly adapted for sewing relatively stretchable fabrics.

While a gear ratio of 2:1 is employed with the gears 41 and 42 it is contemplated that other whole number gear reductions such as 3:] may be used. In this latter case, the machine would make two forward stitch strokes followed by one reverse stroke. A principal feature of the disclosed mechanism 10 is that the various moveable elements are all arranged to move in planes parallel to the pivot plane of the control slide 23 which is perpendicular to the axis of rotation of the main shaft 14. This arrangement results in a kinematically efficient device which is free from complex connections otherwise necessary for accommodating movement in diverse planes. Spring biasing the control slide 23 to a forward feed position and operating on the control slide against the spring force for feed reversal allows the mechanism 10 to be engaged at any time in a feed cycle. Moreover, this arrangement permits an operator to manually shift into full feed reversal by displacing the rod 32 at any time in a feed cycle whether or not the mechanism 10 is operative.

Although a preferred embodiment of this invention is illustrated in detail, it is to be understood that various modifications and rearrangements of parts may be resorted to without departing from the scope of the invention disclosed herein.

What is claimed is:

1. In a sewing machine, a stretch stitch mechanism for alternately forming forward and reverse stitches comprising a feed control slide pivotal in a plane on the frame of the machine, drive means for oscillating the slide in timed relationship with the feed strokes of the machine, said drive means including a gear set having an output gear rotating at a whole number speed reduction relative to the speed of the main shaft of the machine, cam means including a cam rotatably driven by said output gear, means operably connected said cam means and said slide to produce oscillation of the slide, said connecting means including cam follower means movable exclusively in a plane parallel to the plane of the feed slide, and manually controlled means to selectively effect relative movement between the rotatable cam and the follower means within a plane parallel to the slide plane whereby said cam follower means may be rendered effective to oscillate the slide when said manual means is in an operative position and ineffective to oscillate the slide when the manual means is in a nonoperative position.

2. The combination as set forth in claim 1 wherein said manual means includes a manually operable lever pivotal in a plane parallel to said slide plane.

3. The combination as set forth in claim 1 wherein the center of rotation of said cam is stationary with respect to the frame of the machine and said cam follower means is movable toward and away from said center of rotation.

4. The combination as set forth in claim 3 wherein said cam means includes a cam surface moveable with said manual means and adjacent said rotating cam, said cam surface being engageable by said cam follower means when said manual means is in said operative po sition.

5. The combination as set forth in claim 4 wherein said manual means comprises a lever pivotal on the machine frame, said lever having said cam surface integrally formed thereon.

6. The combination as set forth in claim 5 wherein said manual lever is shiftable in a plane parallel to said slide plane, and locking means to maintain said lever in its operative position.

7. The combination as set forth in claim 1 wherein said gear set includes a pair of spur gears.

8. The combination as set forth in claim 7 wherein said spur gears rotate in planes parallel to said feed slide plane.

9. The combination as set forth in claim 1 wherein a spring biases said feed slide towards a first direction and said connecting means is operable to overcome the biasing force of said spring and pivot the slide in a direction opposite said first direction.

10. The combination as set forth in claim 9 wherein said biasing spring maintains said cam follower in contact with said cam means when said manual means is in the operative position.

1 1. In combination in a sewing machine, a main drive shaft, a stretch stitch mechanism for alternately forming forward and reverse stitches comprising a feed control slide pivotal in a plane perpendicular to the axis of rotation of the main shaft, spring biasing means resiliently urging the feed slide in a first angular direction corresponding to a first feed direction, drive means for oscillating the slide in timed relationship with the feed strokes of the machine, said drive means including a first spur gear fixed on the main shaft for rotation therewith and another spur gear driven from the first gear at a whole number speed reduction, cam means including a cam rotatably driven by said other gear,

means operably connecting said cam means and said slide for pivoting said slide, said connecting means in cluding cam follower means movable exclusively in a plane parallel to a plane of the feed slide, said cam fol- 12. The combination as set forth in claim 11 wherein said spring biasing means is arranged to bias said slide to a forward feed position, and including manually operable means for producing reverse feeding independently of the position of the manually controlled means.

13. The combination as set forth in claim 11 wherein said cam means includes a cam surface movable with said manually controlled means-relative to said rotating cam whereby said rotating cam and said cam surface are adapted to displace said cam follower means for oscillation of said control slide only when said manually controlled means is in the operative position.

UNHED STATES PATENT oTTTcE CERTEMQATE GE 'QORRECTION Patent No. 3,796,172 Dated March 12, 1974 ML-mfewfi It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading insert the following:

[32] Priority August 24, 1.971 [33] Japan [31] 76427/71 Signed and sealed this 12th day of November 1974-.

(SEAL) Attest:

MCCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner-of Patents FORM PO-10 USCOMM-DC scam-ps9 U.S. GOVERNMENT PRINTING OFFICE: I969 0-366-334 

1. In a sewing machine, a stretch stitch mechanism for alternately forming forward and reverse stitches comprising a feed control slide pivotal in a plane on the frame of the machine, drive means for oscillating the slide in timed relationship with the feed strokes of the machine, said drive means including a gear set having an output gear rotating at a whole number speed reduction relative to the speed of the main shaft of the machine, cam means including a cam rotatably driven by said output gear, means operably connected said cam means and said slide to produce oscillation of the slide, said connecting means including cam follower means movable exclusively in a plane parallel to the plane of the feed slide, and manually controlled means to selectively effect relative movement between the rotatable cam and the follower means within a plane parallel to the slide plane whereby said cam follower means may be rendered effective to oscillate the slide when said manual means is in an operative position and ineffective to oscillate the slide when the manual means is in a nonoperative position.
 2. The combination as set forth in claim 1 wherein said manual means includes a manually operable lever pivotal in a plane parallel to said slide plane.
 3. The combination as set forth in claim 1 wherein the center of rotation of said cam is stationary with respect to the frame of the machine and said cam follower means is movable toward and away from said center of rotation.
 4. The combination as set forth in claim 3 wherein said cam means includes a cam surface moveable with said manual means and adjacent said rotating cam, said cam surface being engageable by said cam follower means when said manual means is in said operative position.
 5. The combination as set forth in claim 4 wherein said manual means comprises a lever pivotal on the machine frame, said lever having said cam surface integrally formed thereon.
 6. The combination as set forth in claim 5 wherein said mAnual lever is shiftable in a plane parallel to said slide plane, and locking means to maintain said lever in its operative position.
 7. The combination as set forth in claim 1 wherein said gear set includes a pair of spur gears.
 8. The combination as set forth in claim 7 wherein said spur gears rotate in planes parallel to said feed slide plane.
 9. The combination as set forth in claim 1 wherein a spring biases said feed slide towards a first direction and said connecting means is operable to overcome the biasing force of said spring and pivot the slide in a direction opposite said first direction.
 10. The combination as set forth in claim 9 wherein said biasing spring maintains said cam follower in contact with said cam means when said manual means is in the operative position.
 11. In combination in a sewing machine, a main drive shaft, a stretch stitch mechanism for alternately forming forward and reverse stitches comprising a feed control slide pivotal in a plane perpendicular to the axis of rotation of the main shaft, spring biasing means resiliently urging the feed slide in a first angular direction corresponding to a first feed direction, drive means for oscillating the slide in timed relationship with the feed strokes of the machine, said drive means including a first spur gear fixed on the main shaft for rotation therewith and another spur gear driven from the first gear at a whole number speed reduction, cam means including a cam rotatably driven by said other gear, means operably connecting said cam means and said slide for pivoting said slide, said connecting means including cam follower means movable exclusively in a plane parallel to a plane of the feed slide, said cam follower means being operable to overcome the force of said spring biasing means to pivot said slide in the direction opposite said first angular direction, and manually controlled means to selectively effect relative movement between the rotatable cam and the follower means within a plane parallel to the slide plane whereby said cam follower means may be rendered effective to oscillate the slide when said manual means is in an operative position and ineffective to oscillate the slide when the manual means is in an inoperative position.
 12. The combination as set forth in claim 11 wherein said spring biasing means is arranged to bias said slide to a forward feed position, and including manually operable means for producing reverse feeding independently of the position of the manually controlled means.
 13. The combination as set forth in claim 11 wherein said cam means includes a cam surface movable with said manually controlled means relative to said rotating cam whereby said rotating cam and said cam surface are adapted to displace said cam follower means for oscillation of said control slide only when said manually controlled means is in the operative position. 